Effect of Hot End Obstruction and Nozzle on the Performance of Vortex Tube

The vortex tube is a very simple device injected with pressurized air through tangential nozzle which splits in to two streams of low pressure air, one warmer leaves near the periphery at plug end known as free vortex and one colder leaves via an orifice at the opposite end known as forced vortex. The entry and exit of tube are key parameters affecting the performance of vortex tube. The nozzle at entry effects the formation of free vortex flow inside the tube and end region of hot pipe effects the converging of air and controls the forced vortex flow pattern. Providing an obstruction at the end of hot pipe boosts up the desired flow and enhances the energy separation. In the present work an attempt is made to revise the effect of inlet pressure, cold fraction, end obstruction of hot pipe end and also the nozzle on the performance of vortex tube. A series of tubes with different level of obstruction and different nozzle inlet diameters were tested. The results indicate that temperature drop increases with increase of nozzle diameter up to 5mm and no significant improvement is observed beyond it and temperature drop is effective at moderate end obstruction area